Module roaringbitmap

Package org.roaringbitmap

Interface BatchIterator

All Superinterfaces:

Cloneable

All Known Implementing Classes:

RoaringBatchIterator, RoaringBatchIterator

public interface BatchIterator
extends Cloneable

Method Summary

Modifier and Type	Method	Description
void	advanceIfNeeded(int target)	If needed, advance as long as the next value is smaller than minval The advanceIfNeeded method is used for performance reasons, to skip over unnecessary repeated calls to next.
default IntIterator	asIntIterator(int[] buffer)	Creates a wrapper around the iterator so it behaves like an IntIterator
BatchIterator	clone()	Creates a copy of the iterator.
boolean	hasNext()	Returns true is there are more values to get.
int	nextBatch(int[] buffer)	Writes the next batch of integers onto the buffer, and returns how many were written.

Method Details

nextBatch

int nextBatch(int[] buffer)

Writes the next batch of integers onto the buffer, and returns how many were written. Aims to fill the buffer.

Parameters:

buffer - - the target to write onto

Returns:

how many values were written during the call.

hasNext

boolean hasNext()

Returns true is there are more values to get.

Returns:

whether the iterator is exhaused or not.

clone

BatchIterator clone()

Creates a copy of the iterator.

Returns:

a clone of the current iterator

asIntIterator

default IntIterator asIntIterator(int[] buffer)

Creates a wrapper around the iterator so it behaves like an IntIterator

Parameters:

buffer - - array to buffer bits into (size 128-256 should be best).

Returns:

the wrapper

advanceIfNeeded

void advanceIfNeeded(int target)

If needed, advance as long as the next value is smaller than minval The advanceIfNeeded method is used for performance reasons, to skip over unnecessary repeated calls to next. Suppose for example that you wish to compute the intersection between an ordered list of integers (e.g., int[] x = {1,4,5}) and a BatchIterator. You might do it as follows...

     int[] buffer = new int[128];
     BatchIterator j = // get an iterator
     int val = // first value from my other data structure
     j.advanceIfNeeded(val);
     while ( j.hasNext() ) {
       int limit = j.nextBatch(buffer);
       for (int i = 0; i < limit; i++) {
         if (buffer[i] == val) {
           // got it!
           // do something here
           val = // get next value?
         }
       }
       j.advanceIfNeeded(val);
     }
     

The benefit of calling advanceIfNeeded is that each such call can be much faster than repeated calls to "next". The underlying implementation can "skip" over some data.

Parameters:

target - threshold